Photographic stratum transfer process and element therefor



March 5, 1963 H. HAYDN ETAL 3,080,230

PHOTOGRAPHIC STRATUM TRANSFER PROCESS AND ELEMENT THEREFOR Filed Jan.29, 1957 SILZz/erhaZL'de negative emulsion Uuzl includes developer andcan corzlaz'n mozlsture-evolvug irgredzenb.

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Non: lcderalgreversed pas iiive is ikerebyprovided wz'ihoul the useofbodzes ofprooessing INVENTORS lzfildegard Haydn An z'lat Uon/ JCo'u iy FATTORNEYS v. t L fi PHGTO GRAPHHC STRATUM TRANSFER PRGCESS H AND ELEMENTTHEREFOR Hildegard Haydn, Anita von Kiinig, and Edith Weyde',Legregkusen, Germany, assignors to Agra Alitiengese'llso a t Filed .Fan,29, 1-957, Sen.- No; 636,863 Claims priority, application Gerrnany Feb.18, 1956 Claims. (Cl.-96--27) The present inventionrelates to a processfor the direct production of positives by means of silver halideemulsions which are developed by heat without applicatiorr of anyprocessing baths. p I

For the production of non-laterally reversed positive copies, it isalready known to expose a silver bromide halide emulsion layercontaining silver halide developing substances to the object tobereproduced and to heat said exposed material to temperatures of about80450 C. after it is brought into contact with a transfer layer. Withthis procedure, the developing substance, which is contained in thephotographic silver halide emulsion layer and which has remained unusedat the unexposed areas, is" transferred to the transfer layer which isdisposed in contact with the emulsion layer and which contains one ormore substances which yield colored compounds with the said developingsubstance. Oxidizing agents and aromatic diazo and nitro'so compoundsare proposed by way of example as reactants in the positive layer.

It has now been found that direct positives are obtained in a simplemanner if the silver halide developing substances which are usedarethose which so change the binding agent of the silver halide layer withthe reduction of the exposed silver halide that itbecomes" infusible andunswellable, while the unmodified silver halide emuls'ion at theunexposed areas is used for building up the positive image bytransferring the said unmodified silver halide emulsion to the transferlayer and reducing it in the transfer layer to a silver image. Suchsilver halide developing substances are referred to herein as tanningdevelopers.

Suitable silver halide developing substances of this type arepolyhydroxy compounds of benzene, napthalene and diphenyl, which can besubstituted in the nucleus by halogen atoms or alkyl', aralkyl, aryl orcycl-oalkyl groups, for example, pyroca'techol, hydroquinone, 2,3- dihydroxy naphthalene, 2,6-dihyd roxy naphthalene, 3,4- dihydroxy diphenyl,2,3-dihydroxy diphenyl, 1,2-dihyd roxy-'4-cyclohex-yl benzene,4'-benzyl' p'yrocatechol and 4-cloro=pyrocatechol. With the applicationof heat, these developing substances not only reduce the exposed silverhalide, but they also modify the gelatin, probably due to the formationof oxidationproducts, so' that itbecomes infusible and unswellable,while it remains unchanged at the unexposed places. This unmodifiedgelatin of the layer can now be brought during heat develop m'ent or ata later stage into' contact with a second layer which has" the abilityto" adhere firmly to the unmodified gelatin so that, when the two layersare separated, portions of the gelatin are stripped from the negativelayer. In this way, the non=laterally reversed positive of the copiedoriginal is obtained .on the second layer, which is the so-calledtransfer layer, this positive being in the form of a gelatirr reliefwhich still' contains silver halide and developing substance. If thisgelatin relief on the transfer layer is now exposed todiffused light andagain subjected to heat treatment, the record becomes deep black incolor. A- black coloring or the record eaii also be obtained by using anemulsion of appropriate composition or by adding suitable compounds tothe positive layer.

it is" a particillar advantage or the" present process that" both thedevelopment process and the transfer process are effected only by heatand without any additional wet treatment.

The accompanying drawing is a now sheet of the processes describedherein.

Any silver halide emulsion can be used for the production of thenegative layer, such as silver chloride, silver bromide, silverchlorobromide, and silver iodobrom'i'de emulsions. As binding agent, itis possible to use those which are normally used in the photographic artand which are hardened by the action of heat by developer-oxidationproducts, such as for example, gelatin, polyvinyl alcohol, carboxymethylcellulose and mixtures of these substances. The pH value of the emulsionis preferably adjusted to about 3.5-6.5. In order to accelerate' theinitiation of the developing process, it is advisable to add non-tanningsilver halide developing substances, such as p-methyla'rnino phenol,p-amino phenol or their substitution products, to the hardeningdevelopers in amounts up to about 20% by weight as calcul'ated' on thetanning developer.

For stabilizing the developing substances, it is possible to add to thephotographic layers substances which slowly split off sulphur dioxide orsulphurous acid and the cleavage products of which do not cause either ahardening of the gelatin or any other undesirable influencing of thesilver halide emulsion during storage. Examples of such substances arebisu-lphite compounds of such aldehydes or ketones as do not hardengelatin. Particularly suitable for this purpose are aldehydes andketones which have a relatively high boiling point, particularly aboiling point higher than C. Such aldehydes are aromatic, ar'alipha'ticaldehydes, and heterocyclic aldehydes, such as be'nzald'ehyde,terephthalaldehyde, cinn'amaldehyde, salieylaldehyde, furfural, Whereascycloaliphatic ketones, such as cyclope'ntanone and cyclohexanone, andar'aliphat'ic ketones, such as benzala'eetone, and heterocyclicketone's', such as isatin, are the most suitable ketones. Theacetonebisulphite compound would be less suitable, since this substanceonly gives slight protection against oxidation of the developer becauseit has a comparatively strong tendency to decompose with volatilizationof the acetone. Examples of substances which are particularly suitableare: Terephthalaldehyde bisulphite, cinnam'aldehyde bis'ulph'ite,benzal'dehyde bisulph'it'e, salicylal'dehyde bisulphite, cyclohexa'none"bisulphite, cycl'opentanone bisulphite', and f-urfural bi'sulphite,these compounds being preferably used in the form of their alkali-metalsalts, suefr as their sodium, potassium, and lithium salts. The organicdeveloping substances are preferably applied in quantities of about0.5-3 g. per cc. of an ordinary silver halide emulsion, whereas theaforementioned stabil'izers are preferably used in quantities of- O.2-'2parts per part by weight of organic developing substance.

In addition, it is important that compounds splitting off water shouldbe added to the emulsion ofthe negative material or the transfer layer.Suitable additive compounds of this type are salts of inorganie ororganic acids containing water of crystalliiatiorr, such as for example,sodium citrate (C H G Na 51-33 0) sodium acetate (CH COONa-3H O),e'alciuin aeeta'te (ICa-(CH C0O') 2 2H O) trisodium phosphate Na3P04-1'2H 0'), sodium sulphate mason, arid/or substances which ensure ahigh residual moisture content, such as, for example, glycol, glycerol,and sorbit-o'l. These substances are preferably used in such amountsthat thjiwat'er content of the negative material amounts to 8-42,preferably 8-10 percent by weight. When these additives are used in thetransfer layer, the moisture necessary in the development- -or at alater stage.

assesses migrate during the processing from the transfer layer to thenegative layer.

The negative layer can be arranged on any suitable layer support whichis stable at the temperatures usually used for heat development, such asfor example, paper,

plastics, textile fabrics and metals. Between the support and theemulsion, it is advantageous to use an intermediate layer by which theholding strength of the emulsion layer is reduced so that the strippingof the unexposed gelatin is promoted. Particularly suitable for thisintermediate layer are alcohol-soluble heat-resistant substances, suchas ethyl cellulose, polyvinyl pyrrolidone, zein, polyethyl acrylate andpolyvinyl acetate. Any suitable heat-resistant support can be used astransfer layer. The transfer layer can be any suitably coated oruncoated paper, or a plastic, fabric, or metal foil. With coatedtransfer papers the coating of the said paper can contain additiveswhich split off water and also additives by which the transferred recordis blackened, such as, for example, nitrogen-containing organiccompounds as, for instance, N-diethyl aminoethanol, triethanolamine,tetrarnethyl am- -monium hydroxide, pyridine, piperazine, hydrazine, orcompounds containing sulphur, such as thioacetarnide. -These additivesmay be used in quantities of about 1-10 g. per g. of binding agent,although other proportions are useful.

The production of the positive or the transfer process can either takeplace together with the developing process Furthermore, several copiescan be made from the negative, this taking place immediately after thefirst transfer or at different later stages. However, care should betaken that the negative is not exposed to light in the interveningperiod.

EXAMPLE 1 Negative Zayer. g. of pyrocatechol, dissolved in a smallamount of water, 10 g. of terephthalaldehyde bisulphite, 200 g. ofsodium acetate containing water of crystallization (CH COONa-3H O) and0.05 g. of benzotriazole are added to 1 liter of any desired silverhalide emulsion. Other additives known in the emulsion art can also beused. The emulsion is cast on paper or another layer support and dried.

Transfer layer.A 1% solution of acetyl cellulose acetobutyrate inacetone is cast on a layer support, such as, for example, paper, andthen dried. It is advisable to add a plasticizer such as a phthalic acidester, to the layer.

Processing.After exposure to an image, the negative is brought intocontact with the transfer layer. The negative and transfer layer arethen subjected to a temperature of 90 to 150 C., preferably l10l20 C.,for 5 to seconds in a hot press. The transfer layer can be heated at alower temperature. After separation, the gelatin of the unexposed areasadheres to the transfer layer. After subsequent exposure thereof withdiffused light and after reheating, a deep black unreversed positive isobtained of the original image.

EXAMPLE 2 Negative layer.-20 g. of pyrocatechol and 2 g. ofprnethylaminophenol sulfate in a small quantity of Water, are added to 1liter of any desired silver halide emulsion. This emulsion has addedthereto 6 g. of cyclohexanone bisulphite, 180 g. of sodium acetatecontaining Water of crystallization, and 0.05 g. of benztriazole orcorresponding amounts of other stabilizers. This emulsion is cast on asupport as in Example 1 and dried.

Transfer layer.A 1% alcoholic solution of acetyl cellulose has 5 g. ofpiperazine per liter added thereto. The solution is cast on a supportand dried.

Processing-T he processing takes place as in Example 1, but theafter-treatment of the positive is superfluous since blackening of thetransferred layer is effected by the piperaziue.

4 EXAMPLE 3 Negative layer.25 g. of 4-cyclohexyl pyrocatechol, dissolvedin 30 cc. of dimethyl formamide, are added to one liter of any desiredsilver halide emulsion. 10 g. of terephthalaldehyde bisulphite, 225 g.of sodium acetate containing Water of crystallization, 0.05 g. ofbenztrilazole, and 0.03 g. of phenyl mercaptotetrazole are then added tothe emulsion, which is then cast on a support as in Example 1 and dried.

Transfer layer.A 2% solution of a copolymer of 30% acrylic acid and 70%of methyl methacrylate in dimethyl formamide is cast on a layer supportand dried.

.Pr0cessing.--As in Example 1.

EXAMPLE 4 Negative layer.22 g. of monotertiary butyl pyrocatechol areintroduced into 1 liter of silver chloride emulsion and then to theemulsion is added 200 g. of sodium acetate containing water ofcrystallization and 5.5 g. of cyclopentanone bisulphite. Stabilizers andother known additives such as wetting agents can be added.

Transfer layer.A 3% solution of polyacrylonitrile in dimethyl formamideis cast on a layer support and dried.

Pr0cessing.-As in Example 1.

EXAMPLE 5 Negative layer.-20 g. of pyrocatechol, dissolved in a smallquantity of water.

I l g. of pmethylaminophenolsulphate 8 g. of salicylaldehyde bisulphite0.08 g. of benztriazole 0.02 g. of phenyl mercapto tetrazolc and 15 cc.of glycerol are added to each liter of a silver halide emulsion.

This emulsion is cast on a support :as in Example 1 and dried.

Transfer Iayer.3 cc. of N-diethyl aminoethanol are added to liter of a3% alcoholic solution of a condensation product obtained fromhexamethylene diamine adipate and caprolactam(epsilon-caprolactam).

Pr0cessing.-As in Example 2.

EXAMPLE 6 Negative [cyan-The starting material is a silver halideemulsion in which 10 to 30% of the normal gelatin is replaced by one oflower constants, i.e. and a gelatin which has been partially degradedas, for instance, by heating an aqueous solution of gelatin at atemperature of 80 C. for several hours. Developer and additives can bethose of Examples 2-5.

Transfer layer.A fine mesh fabric such as silk gauze or plastic fabricis suitable as positive material. The fabric can also be coated with oneof the aforementioned plastic solutions.

Processing.As in Example 1.

EXAMPLE 7 Negative layer.The starting material is a silver halide iemulsion in which 15% of the gelatin is replaced by polyvinyl alcohol.The additives can be the same as in the preceding examples.

Transfer layer.-One of the layers described above is used as positivelayer, and the processing then takes place accordingly.

EXAMPLE 8 scribed is used as positive and also an ordinary piece ofWriting paper.

Processing-As in Example 1.

EXAMPLE 9 A silver chloride emulsion with the following additives perliter of emulsion is used for producing the negative layer:

20 g. of pyrocatechol, dissolved in a small amount of water,

10 g. of terephthalaldehyde bisulphite,

0.1 g. of nitrobenzimidazole, and also 0.05 g. of mercaptobenzthiazole.

Transfer layer.The paper is impregnated with a 10% sodium acetatesolution and is then used as the transfer paper. On being heated, thispaper gives oif a certain amount of water which accelerates thereactions.

PrcessingAS in Example 1.

EXAMPLE 10 Negative layer.--

20 g. of 2,3-dihydroxy naphthalene,

g. of te-rephthalaldehyde bisulphite,

0.05 g. of henztriazole,

0.02 g. of mercaptobenzthiazole,

g. of sodium acetate trihydrate (CH COONa-3H O),

and

5 g. of sorbitol are added to each liter of a silver chlorobromide orsilver chloride emulsion.

This solution is cast onto a paper which has been treated beforehandwith a 1% alcoholic solution of ethyl cellulose.

Transfer layer.Any desired writing paper can be used.

Processing.-After exposure, the negative is brought into contact withthe transfer layer. The negative and transfer layer are then passedbetween two heated rollers, in which they are subjected to a temperatureof approximately 90 to 150 C. The two layers are then quickly pulledapart, only some of the unexposed negative layer remaining adhering tothe positive (transfer) paper. The operation can be repeated 3 or 4times in the same way. The thickness of the negative layer is ofimportance, since it is possible to produce more copies with a thickercoating of negative layer.

We claim:

1. A photographic material for preparing positive photographic imageswithout the use of bodies of processing liquid, said material includinga support and a light-sensitive tannable silver halide emulsion layer onthe support, the emulsion layer containing an effective amount of atanning delevoper, a non-tanning developer in an amount effective toaccelerate the initiation of the development, and for every part byweight of developer about 0.2 to 2 parts by weight of a bisulphite of acompound selected from the group consisting of aldehydes and ketonesthat have a boiling point above 80 C. and that do not harden theemulsion.

2. A photographic material for preparing positive photographic imageswithout the use of bodies of processing liquid, the said materialincluding a support and a lightsensitive tannable silver halide emulsionlayer on the support, the emulsion layer containing an effective amountof a tanning developer, a compound that evolves moisture at atemperature between 80 and 150 C. and in a concentration such that thewater content of the emulsion is from 8 to 12%, and a bisulphite of acompound selected from the group consisting of aldehydes and ketonesthat have a boiling point above 80 C., the bisulphite being present in aconcentration between 0.2 and 2 parts by weight for each part by weightof the developer.

3. A process for the product-ion of non-laterally-reversed positivephotographic images without the use of bodies of processing liquid,which process comprises exposing to an original image a light-sensitivesilver halide emulsion layer containing a tanning developer that causesthe emulsion to be tanned in its photographically exposed areas whendeveloping action takes place, and also containing, in an amount between0.2 and 2 parts by weight per part by weight of the developer, abisulphite of a compound of the group consisting of aldehydes andketones that have a boiling point above C. and that do not harden theemulsion layer, pressing the exposed emulsion layer against a transferlayer at a temperature between about 80 and C., at least one of thesetwo layers containing a moisture-evolving compound that providessufficient water for the hot pressing to effect development and to causeundeveloped portions of the emulsion layer to adhere to the transferlayer, and thereafter separating the transfer layer from the emulsionlayer so that the transfer layer removes the adherent portions of theemulsion layer and provides the desired photographic image.

4. A process as defined in claim 3 in which the moisture-evolvingcompound contains water of crystallization.

5. A process defined in claim 3 in which the moistureevolving compoundis hydrated sodium acetate.

6. A process defined in clam 3 in which the moisture is supplied byincorporating in one of the layers a moistening compound selected fromthe class consisting of glycol, glycerol and sorbitol.

7. The process of claim 3 in which the transferred portions of theemulsion are made darker in appearance.

8. The process of claim 3 in which the emulsion contains a non-tanningdeveloper in addition to the tanning developer, and the transferoperation is conducted under conditions that cause the non-tanningdeveloper to darken the transferred portions of the emulsion.

9. A process as defined in claim 3 in which the transfer layer containsa blackening agent that causes the blackening of the transferredportions of the emulsion.

1-0. A process defined in claim 9 in which the blackening agent isselected from the class consisting of N-diethylaminoethanol,triethanolamine, tetramethylammonium hydroxide, pyridine, piperazine,hydrazine, and thioacetamide.

References Cited in the file of this patent UNITED STATES PATENTS742,405 Eichengriin Oct. 27, 1903 1,954,325 Martinez Apr. 10, 19342,596,756 Yutzy et al. May 13, 1952 2,675,313 Yutzy et al. Apr. 13, 19542,716,059 Yutzy et al. Aug. 23, 1955 2,747,999 Yutzy et al. May 29, 19562,835,575 Cowden et al. May 20, 1958 2,865,745 Chan et al. Dec. 23, 1958FOREIGN PATENTS 2,971,840 Germany Feb. 14, 1961 392,938 Great BritainMay 26, 1933 399,269 Great Britain Oct. 5, 1933 427,962 Great BritainApr. 29, 1935 OTHER REFERENCES 70 Henry Holt, 1947, p. 152..

UNITED STATES PATENT OFFICE QERTIFICATE ()F CORRECTION Patent N00 3 080230 March 5 1963 Hildegard Haydn et ale It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

Column 1 line 43 for "napthalene" read naphthalene line 5O for"4010r0-pyrocatechol read d chloro pyrocate ch01 column 2 line 64L for(Na3POd-12H O)" read um (Na PO 12H O) line 65 for "(Na SO read W (Na SO-1OH O) a Signed and sealed this 1st day of October 1963,

(SEAL) Attest:

I Attesting Ufficer ERNEST We SWIDER. DAVID L LADD Commissioner ofPatents 4

3. A PROCESS FOR THE PRODUCTION OF NON-LATERALLY-REVERSED POSITIVEPHOTOGRAPHIC IMAGES WITHOUT THE USE OF BODIES OF PROCESSING LIQUID,WHICH PROCESS COMPRISES EXPOSING TO AN ORIGINAL IMAGE A LIGHT-SENSITIVESILVER HALIDE EMULSION LAYER CONTAINING A TANNING DEVELOPER THAT CAUSESTHE EMULSION TO BE TANNED IN ITS PHOTOGRAPHICALLY EXPOSED AREAS WHENDEVELOPING ACTION TAKES PLACE, AND ALSO CONTAINING, IN AN AMOUNT BETWEEN0.2 AND 2 PARTS BY WEIGHT PER PART BY WEIGHT OF THE DEVELOPER, ABISULPHITE OF A COMPOUND OF THE GROUP CONSISTING OF ALDEHYDES ANDKETONES THAT HAVE A BOILING POINT ABOVE 80* C. AND THAT DO NOT HARDENTHE EMULSION LAYER, PRESSING THE EXPOSED EMUL-